The code that calculates the legacy ACPI table size for migration
compatibility uses max_cpus when calculating legacy_aml_len (the size of
the DSDT and SSDT tables). However, the SSDT grows according to APIC ID
limit, not max_cpus.
The bug is not triggered very often because of the 4k alignment on the
table size. But it can be triggered if you are unlucky enough to cross a
4k boundary. For example, using the following:
$ qemu-system-x86_64 -machine pc-i440fx-2.0 -smp
99,sockets=3,cores=33,threads=1
qemu-system-x86_64: Warning: migration may not work.
Change the legacy_aml_len calculation to use apic_id_limit, to calculate
the right size.
Signed-off-by: Eduardo Habkost <ehabk...@redhat.com>
---
hw/i386/acpi-build.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
index a4d0c0c..359fb43 100644
--- a/hw/i386/acpi-build.c
+++ b/hw/i386/acpi-build.c
@@ -1675,7 +1675,7 @@ void acpi_build(PcGuestInfo *guest_info, AcpiBuildTables
*tables)
*/
int legacy_aml_len =
guest_info->legacy_acpi_table_size +
- ACPI_BUILD_LEGACY_CPU_AML_SIZE * max_cpus;
+ ACPI_BUILD_LEGACY_CPU_AML_SIZE * guest_info->apic_id_limit;
int legacy_table_size =
ROUND_UP(tables->table_data->len - aml_len + legacy_aml_len,
ACPI_BUILD_ALIGN_SIZE);
--
1.9.3
